Calcutta, March 7: Congress councillor Mala Roy and one of her party colleagues in the Calcutta Municipal Corporation today defected to the Trinamul Congress in the run-up to the civic elections.

With the defections of four-time councillor Roy, who was the Congress's south Calcutta district president, and Arun Das, councillor from Ward 55 in the Entally-CIT Road area, the party is left with just two representatives in the 144-member civic board.

Last week, a Congress councillor from north Calcutta, Suman Singh, had switched to Trinamul.

Congress leaders expressed "shock" at the defection by Roy, who had switched to the party from Trinamul in 2005. They said Roy had toed the state unit line last month and protested against Congress leader Kapil Sibal's decision to accept Trinamul's brief in its appeal in the Supreme Court in the Saradha probe.

"Mala's decision is shocking because she was most vocal against Sibal. It appears she has switched to Trinamul realising she won't be able to win the civic polls on a Congress ticket," state Congress president Adhir Chowdhury said.

Roy, who unsuccessfully contested the Calcutta South Lok Sabha seat in last year's general election, held Chowdhury responsible for her defection.

"I have been a four-time councillor since 1995. But last week, I was told to submit my bio-data at the state Congress office for re-nomination for the civic polls. I felt insulted," she said.

Roy accused Chowdhury of "ruining the organisation" in Bengal. "Despite being the president of the party's south Calcutta unit, I was not asked to attend last month's meeting at the state Congress headquarters, where (AICC general secretary and Bengal Congress minder) C.P. Joshi was present to discuss the probable nominees for the civic elections," she said.

She denied that her grouse against the state Congress president was the sole reason for her defection.

"I had no job in the Congress. My association with Trinamul would at least help me join Mamata Banerjee's development agenda," she said.

Roy today went to Nabanna from the civic headquarters to meet the chief minister following a "call" from her last night.

After half an hour, she went to Trinamul Bhavan in Topsia and joined the party in the presence of newly appointed all-India general secretary Subrata Bakshi, secretary-general Partha Chatterjee and mayor Sovan Chatterjee.

"Mala's return to Trinamul is a homecoming for her. She was with us when the party was founded in 1998," Partha Chatterjee said.

A Trinamul general secretary said Sovan Chatterjee had engineered Roy's defection at Mamata's behest.

Roy's husband Nirbed, who is with the Congress, said: "At Mamata's behest, Sovan had been coaxing Mala for the past six months to switch to Trinamul."

Asked if he would follow suit, Nirbed said: "I am still with the Congress. But I can tell you this much that I'm not at all happy with the state of affairs in the Bengal Congress. The party has become non-functional in the state because of the absence of the PCC chief from his office."